1. Field of the Invention
The present invention relates to a disc changer, which permits to identify the type of a disc magazine loaded therein to setup rapidly a system without carrying out an unnecessary identification process.
2. Description of the Related Art
In the conventional prior art, a disc magazine, which permits to store a plurality of discs in a disc changer, has no reliable locking mechanism. For example, the conventional disc magazine merely has s leaf spring by which the disc can be held.
There is a possibility that the disc may come down from the disc magazine, when the disc magazine is in the off-line condition, i.e., it is unloaded from the disc changer, and a strong impact force is applied to the disc magazine. The exchanging operation of the disc can easily be carried out in a condition in which the disc magazine is unloaded from the disc changer.
However, if once the coming down or the exchange of the disc occurs, it is necessary to reassemble a data base by detecting the existence of the respective discs in the disc magazine, reproducing partially the information recorded on the disc, and carrying out the other steps, in condition that the disc magazine is reloaded in the disc changer.
The reassembly of the database requires much time. The required time becomes longer, according as the number of discs to be stored in the disc magazine increases. In case many discs exist, an extremely long period of time is required in order to start a system operation.
An object of the present invention is therefore to provide a disc changer, which permits to reduce the required time in order to start a system operation.
In order to attain the aforementioned object, a disc changer of the present invention, which has at least one slot in which any one of different kinds of disc magazines can be stored, comprises:
a first device for identifying a type and an identification number of said disc magazines;
a second device for detecting existence of a disc in each of said disc magazines;
a third device for reading information recorded on said disc, which is stored in each of said magazines; and
a fourth device for storing a data table, which includes the information on the type and the identification number of said disc magazines and on the existence of said disc in each of said disc magazine.
The above-mentioned different kinds of disc magazines may comprise a lock-type disc magazine in which the disc cannot be lodged or dislodged outside the disc changer and a normal-type disc magazine in which the disc can be lodged or dislodged outside the disc changer when the normal-type disc magazine is in an unlocking state.
The above-mentioned first device may comprise (1) a control unit being capable of achieving a setup operation for the disc changer and (2) a memory provided in each of said disc magazines; the above-mentioned second device and said third device may comprise a plurality of disc driving devices for the disc in each of said disc magazines; and the above-mentioned fourth device may comprise a memory provided in the disc changer.
Each of the above-mentioned disc driving devices may comprise a pickup, a spindle motor, a spindle driver, a laser drive circuit, a power control circuit, an encoder, a reproduction amplifier, a decoder, a processor (CPU), a reference clock signal generator for generating a base clock signal for rotation control, a prepit signal decoder, a phase comparator for generating a rotation control signal, a recording clock signal generator and an interface for interchanging data relative to a external host computer.
The above-mentioned first device may comprise (1) a control unit being capable of achieving a setup operation for the disc changer and (2) a memory provided in each of said disc magazines; the above-mentioned third device may comprise a plurality of disc driving devices for the disc in each of said disc magazines; the above-mentioned second device may comprise a disc transferring device for transferring the disc between said disc magazines and said disc driving devices; and the above-mentioned fourth device may comprise a memory provided in the disc changer.